1. Field of the Invention
The invention concerns a method and a device for producing the hull of a piece of water sports equipment. The hull is produced by a thermoplastic molding process. The invention also concerns a piece of water sports equipment.
2. Description of the Related Art
Numerous plastic products are inexpensively produced from thermoplastics by thermoplastic molding processes such as the blow molding process, the rotational molding process, the twin sheet molding process, or the deep drawing molding process. A blow molding process has the advantage over a rotational molding process, for example, that it is less expensive to carry out and can achieve better material properties of the blow molded product. However, especially in the case of boat hulls, openings and areas around openings cannot be molded as desired, and therefore specific requirements cannot always be satisfactorily met.
In addition, there is the problem that, due to the essentially uniform wall thickness of thermoplastically molded boat hulls, it is not possible to construct areas in the hull that have any desired degree of stability. For example, areas in which a relatively large force is introduced into the hull are finished by subsequently welding additional material onto the hull in these areas or by mounting additional elements. Examples of areas of this description include especially grips provided on the hull or holes provided in the hull for fastening a line. In other areas in which instability generally does not lead directly to destruction of the hull, this instability is often accepted for cost reasons.
In the prior art, in the hull of a piece of water sports equipment, e.g., the hull of a canoe, grip projections and bilge plug formations are subsequently reinforced by the application of additional material. Especially in kayaks, coaming is provided around the cockpit opening, and a spray cover can then be attached to the coaming. This coaming is either reinforced by installing stiffening ribs or is intentionally left unstable. However, if the coaming is unstable, the spray cover cannot be reliably prevented from slipping off. Furthermore, additional molded parts must be subsequently mounted and fastened for the installation of a back support and to realize leg supports.